1. Field of the Invention
The subject invention generally relates to a foam dispensing apparatus for dispensing a mixture of a first fluid and a second fluid. More specifically, the subject invention relates to a manifold assembly for supplying the first fluid, the second fluid, a gas and a cleansing fluid to a dispensing head of the foam dispensing apparatus.
2. Description of the Related Art
Expanding chemical foam compositions, such as curable polyurethane foams, are presently well known and used in a number of different applications. Expanding chemical foam compositions are useful in such applications as thermal insulation, floatation, coatings and packaging. The curable foam compositions comprise a two-part composition, and in the case of polyurethane foams, one part of the composition includes a resin component and the other part includes an isocyanate component. The resin component typically includes a polyol component. Chemical foaming agents, curing agents catalysts or accelerators, as well as other modifying additives, may be incorporated into one or both of the foam components. These two-components of the foaming composition are separately stored in different containers until use.
In use, the two components of the foam composition are rapidly mixed together. A rapid cross-linking reaction and foam expansion commences, which ultimately yields a low density, but relatively high load bearing urethane rigid foam. The mixing of the resin component and the isocyanate component must occur at a proper flow ratio and mix under rapid and sufficient impingement mixing conditions to obtain a final acceptable product.
The urethane components, including the resin component and the isocyanate component, are stored under pressure in containers, which are attached to hand held dispensing assemblies (guns) by means of various hoses and couplings. The guns include a trigger operated dispensing head designed to permit the two-components of the foam composition to flow into a mixing chamber wherein the two components are rapidly mixed to form a reactive and expanding chemical foam composition, which exits through a foam discharge nozzle or opening. The trigger operated dispensing head may be manually controlled or electronically controlled.
The two components of the foam composition are highly chemically reactive and begin to form a cured polymeric product within a matter of seconds. Premature leaking and mixing of the two foam components within the dispensing assembly is a serious and major concern because leakage results in undesirable curing in the dispensing assembly, causing blockage and damage to dispensing assembly.
Referring to Prior Art FIG. 1, an example of a prior art dispensing assembly (gun) is shown. The dispensing assembly comprises a dispensing head, which dispenses the mixed foam composition. The dispensing assembly further comprises various pipe fittings and tubing to provide the two foam components to the dispensing head. Additionally, the dispensing assembly further comprises various pipe fittings to provide a flow of a gas, preferably but not limited to nitrogen, and a flow of a cleansing fluid, preferably but not limited to water, to the dispensing head. The gas is entrained within the foam components to assist in the formation of the expanded foam product and may be utilized to flush or clean the dispensing head. The cleansing fluid is also utilized to flush the remnants of the foam components from the dispensing head at the end of each use. The gas may be combined with the cleansing fluid to assist in cleansing the dispensing head. The various pipe fittings and components include on/off control valves, check valves, flow control valves, couplings, T-connectors, etc. Each of the connections between the various components is susceptible to leakage. Additionally, dispensing assemblies such as shown in Prior Art FIG. 1 are heavy and awkward to handle.